Whereas the options are limited for differentiating graphical elements, you can differentiate texts any way you wish. Nuances are used to express causality in language. Graphics, however, provide no room for leeway. Due to the complexity of the financial crisis, diagrams that primarily avoid text quickly become grotesque because they simplify the world to a point where we can no longer recognize it. If we simplify things too much, they might not make sense any more.